As the highest-ranked American in men's tennis, Sam Querrey watches all of the recent success by players in their 30s and likes what he sees.

Men 30 and older made a big splash at the Sony Open last week, including semifinalist Tommy Haas, at 34 the oldest player in the ATP World Tour's top 50, and runner-up David Ferrer, who lost a thrilling final to Andy Murray. Serena Williams, 31, became the oldest women's champion.

It's a trend that might continue into the clay-court season that began Monday, and beyond.

"I think about it — Haas at 34," Querrey said. "Hey, I'm 25. I really hope that I can go for nine good more years. It gives me more motivation and more hope that I can have a nice, long career like those guys."

The Sony Open had 22 30-something men in the draw, compared with 12 a decade ago. Twenty years ago, there were only four men 30 or older.

Ferrer, who turns 31 on Tuesday, and 31-year-old Jurgen Melzer staged the first all-30-something men's quarterfinal at Key Biscayne since 2003. Add Haas, and for only the third time since 1990, three men 30 or older reached the quarterfinals of a Masters 1000 event.

"It has been quite interesting," said Murray, 25. "Guys are reaching their peak later in their careers. The average age at the top 100 has increased by a few years since I first came on the tour."

Bjorn Borg retired at 25. Boris Becker was done playing full time at 28. Patrick Rafter quit at 28, and Marat Safin and Gustavo Kuerten walked away at 29. Andy Roddick retired last year shortly after turning 30.

But the style of play has changed, with trips to the net much more infrequent than in the past. Top players can win by hugging the baseline.

"A lot of the guys that used to play serve and volley had a lot of problems with their backs and their knees and hips, and finished when they were 28 or 29 years old," Murray said. "And now guys are probably training better. There are better training methods, and people probably understand how to recover from matches better and are learning new things all the time about how the body works."

The No. 1-ranked Williams joked last week about buying a Rolls-Royce in response to a mid-life crisis when she turned 30. But she might be more dominant than ever, and her conditioning seems at a peak for the challenges of clay.

Two other 30-somethings are ranked in the women's top 15 — Li Na and Roberta Vinci, a late-bloomer ranked a career-high No. 13 at age 30.

As tennis takes on a more mature look, teen sensations are becoming less common. On the men's side, Becker was a two-time Wimbledon champion before he turned 20. Mats Wilander won his first major title at 17, Borg at 18, Pete Sampras at 19.

But the most recent teenage men's Grand Slam champion was a 19-year-old Rafael Nadal at the 2005 French Open.

Again, Querrey sees changes in the style of play as a factor.

"Compared to 20 years ago, I think guys can hit the ball bigger now," he said. "A man can just overpower and blow away an 18-year-old boy. I think 20 years ago with the rackets and the way people played, guys couldn't just blow through an 18- or 19-year-old. Guys weren't big power guys. You couldn't hit the ball through players as much, so it allowed some of the younger players to feel their way into the game.

"Nowadays I feel that's tougher to do. There is a bigger difference between the way a bigger, stronger man plays compared to an 18- or 19-year-old."

Haas, who turns 35 on Wednesday, is a muscular 6-foot-2 and 190 pounds. And he's No. 14 this week, the highest he has been ranked in five years.

The German said he and other 30-somethings on the tour know how to take care of their bodies and are properly conditioned.

"I think what it comes down to is the older you get, you would assume you get wiser," he said. "Now with nutrition and everything you can do, the right training, the trainers that you have, it just helps you mentally.

"You just know what works for you best. You might do a lot of lifting; you might do a lot of cardiovascular workout. You try to figure out what helps you the best if you want to keep on riding it for as long as you can."